A time that I often use acronyms is PEMDAS for math. PEMDAS stands for Parentheses Exponents Multiply Divide Add Subtract. This particular acronym is used for simplifying expressions with 2 or more operations. This was a very useful technique because it really stuck in the brain and helped me remember which order to simplify the expression.
Hope this helps :)
Your answer is 0.23 because your tenth place is where the 3 is so you need to look if it is higher or lower than 5